/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.sourceforge.docfetcher.model.search;


import java.io.IOException;

import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.LeafCollector;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.SimpleCollector;


/** A simple delegating collector where one can set the delegate after creation */
public class DelegatingCollector extends SimpleCollector {

    /* for internal testing purposes only to determine the number of times a delegating collector chain was used */
    public static int setLastDelegateCount;

    protected Collector delegate;
    protected LeafCollector leafDelegate;
    protected Scorer scorer;
    protected LeafReaderContext context;
    protected int docBase;

    public Collector getDelegate() {
        return delegate;
    }

    public void setDelegate(Collector delegate) {
        this.delegate = delegate;
    }

    /** Sets the last delegate in a chain of DelegatingCollectors */
    public void setLastDelegate(Collector delegate) {
        DelegatingCollector ptr = this;
        for(; ptr.getDelegate() instanceof DelegatingCollector; ptr = (DelegatingCollector)ptr.getDelegate());
        ptr.setDelegate(delegate);
        setLastDelegateCount++;
    }

    @Override
    public void setScorer(Scorer scorer) throws IOException {
        this.scorer = scorer;
        if (leafDelegate != null) {
            leafDelegate.setScorer(scorer);
        }
    }

    @Override
    public boolean needsScores() {
        return delegate.needsScores();
    }

    @Override
    public void collect(int doc) throws IOException {
        leafDelegate.collect(doc);
    }

    @Override
    protected void doSetNextReader(LeafReaderContext context) throws IOException {
        this.context = context;
        this.docBase = context.docBase;
        leafDelegate = delegate.getLeafCollector(context);
    }

    public void finish() throws IOException {
        if(delegate instanceof DelegatingCollector) {
            ((DelegatingCollector) delegate).finish();
        }
    }
}
